Once the Prophet (s.a.w.a.) went to the dumps of some people and passed urine while standing. He then asked for water and so I brought it to him and he performed ablution.

Hudhaifa reported:

I was with the Messenger of Allah (S) when he came to the dumping ground of filth belonging to a particular tribe. He urinated while standing, and I went aside. He (the Holy Prophet) asked me to come near him and I went so near to him that I stood behind his heels. He then performed ablution and wiped over his socks.